The suspension apparatus for work implements such as rotary brushes and ploughs intended to be mounted on a vehicle are already widely known. A common problem with this type of work implement is that it is required to follow an uneven underlying surface whilst maintaining ground clearance or a certain surface pressure. One prerequisite for this is the facility for raising and lowering the work implement vertically whilst at the same time being able to angle it in relation to the suspension apparatus.
U.S. Pat. No. 4,926,517 discloses an apparatus which has a suspension apparatus for a cylindrical sweeping roller. The sweeping roller is fixed into a carrier which also supports a hydraulic motor and a protective hood for the roller. The carrier is fixed to the vehicle by way of a number of linkages and a hydraulic cylinder, which is capable of raising and lowering the sweeping roller in relation to the underlying surface. This means that the operating apparatus must lift a relatively large weight. Furthermore, this apparatus cannot be angled in relation to the carrier in order to follow an uneven surface.
US 2002/0078516 discloses an apparatus having a sweeping roller which can be raised and lowered and can be angled in relation to the holder. In this case, too, an operating apparatus in the from of a hydraulic cylinder must lift a relatively large weight, including the sweeping roller, a pair of drive motors, a protective hood, and a carrier for this combined assembly. In addition to this, the carrier of the sweeping roller is suspended in a holder located above the centre of gravity of the assembly. This means that the suspension is exposed to relatively large torques if the sweeping roller encounters an obstacle or is used with a high surface pressure against the underlying surface. In order to cope with these stresses it may be necessary to design the suspension apparatus accordingly, which can result in a further increase in the sprung weight.
One problem with known solutions, therefore, is that the forces occurring in the use of a work implement can give rise to relatively large torques in the suspension apparatus. These torques can in turn cause increased wear of the moving parts of the suspension and can limit the maximum surface pressure of the work implement against the underlying surface.
A further problem is that work implements which can be both raised and lowered, and independently tilted at each end are often relatively heavy. The fact that the frame, the carrier and the work implement are often mounted in the same unit means that the weight that has to be sprung in order to maintain a certain height or a certain surface pressure is relatively large. This can in turn give rise to increased wear of implements such as rotary cylindrical brushes and ploughs. A heavy unit will also require more force and take longer to avoid edges and larger irregularities in the underlying surface, which may result in more serious damage to or deformation of the work implement.
The apparatus according to the invention solves the problems outlined above.